Quantitative measurement of spinal motion in the lower back or lumbar region is vital in evaluating and treating physical impairment in this area, whether due to trauma, degenerative disease, or other causes. Because small inaccessible spinal joints do not readily lend themselves to the external visual observations typically required by standard goniometric measurement processes, such techniques for measuring spinal movement have been recognized to be highly inaccurate.
The mobility of spinal segments is confounded by motion above and below the points of measurement. The complexities involved in measuring spinal movement in the lumbar region have led to the development of large and cumbersome apparatuses which are not only expensive, but substantially reduce the ability of a subject to move normally during their use.
U.S. Pat. No. 5,146,929 to Sawhill, which is incorporated by reference herein, describes a device designed to provide a system for measuring the range of motion in the lumbar spinal region without use of visual techniques or cumbersome physical equipment that limits the activities of the subject.
While the device of the Sawhill patent is intended to measure all three lumbar angles of movement, it incorrectly assumes a relationship between the three axis of measurement which the device provides and actual lumbar movement. The resulting inaccurate determinations result from inadvertent motion of one axis of measurement caused by movement of one of the other axis. In other words, it has been found that the three axis of movement measured by the Sawhill device are not totally independent of one another and therefore cannot be used alone for accurately determining the corresponding three angles of Lumber motion.
It is accordingly an object of the present invention to provide an improved, portable device for quantitatively determining movement in the lumbar region of the spine which eliminates erroneous measurements resulting from mechanical coupling of the three axis of measurement associated with the three angles of lumbar movement.
It is a further object of the invention to provide an improved device for accurately determining lumber movement which compensates for inaccuracies in device of the prior art by providing for measurement of movement using additional sensors to calculate accurately the three lumbar angles of movement.